Apparatus for the treatment of acid sludge



June 8, 1943. W. F. CARR ET AL 2,321,457

APPARATUS FOR THE TREATMENT OF ACID SLUDGE Filed Sept. 28, 1938 Patented June 8, 1943 APPARATUS Fort 'rnn or Acm swoon Walter. Frederick Carr, Thomas Geoffrey Woolhouse. and William Green, near Bother-ham, England Wath-upon- Dcarne,

Application September 2a, 1938, Serial-No. zsaua in Great Britain October 4, m7

2 Claims. (01. 23 2s g This invention relates to the treatment of. acid sludge from the refining of spirit recovered from the carbonisation of coal, hereinafter termed benzol refining, and has for its main object to provide an improved which hydrocarbons an dilute acid are recovered from the acid sludge and the escape of noxious fumes to atmosphere may be entirely prevented.

The invention comprises a method'and apparatus for the treatment of acid sludge from bensol refining in which the acid sludge is steam treated in a treatment-vessel to, remove the desired hydrocarbons together with sulphurous and water vapours, the remaining contents oi the treatment vessel being maintained at elevated temperature to enable the separation of the resin and acid liquor into layers; thelayers being run oil separately with the resin still in the liquid state.

The invention' is more particularly concerned with the treatment of acid sludge obtained during benzol refining'and one method of and plant for carrying the invention into eilfect in connec-' tion with such refining will now be described, by way of example, with reference to the accompanying drawing in which:

Figure 1 is a hoot elevation of an acid sludg treatment plant constructed the invention, and

Figure 2 is a side elevation of the plant shown in Figure 1. i

in accordance with ethod and apparatus by thesteam to the upper end of the cracker pipe 9, .the perforated part lo of which is immersed in the sludge. Pressure gauges ii and i! are provided on the pipe i and treatment vessel 6 respectively. 4

The benzol, water vapour and "sulphurous fumes generated during steaming are conducted from the top of the treatment vessel by a swan neck l3 to the scrubber condenser 4. The upper part of the latter consists of a column ii packed with Raschig rings i8 or other suitablepacking. water being fed to the upper end of the column by a valved pipe i'i through a spray l8. The-- watercondenses the benzol and water vapour Y and dissolves the acid fumes and the mixture of water and benzol is run from the base of the scrubber condenser into a separator I! where the benzol is recovered and passed to a calibrated storage through a pipe 20 while the water is run to waste through a pipe 2 i. The water fed to the scrubber condenser through the pipe ll has an alkaline reaction, the alkalinity being so arranged as. to absorb any acid vapours produced in the distillation process, the waste water being neutral. or substantially neutral.

The operation of the process is carefully controlled insofar that the minimum of free steam; that is the low pressure steam admitted to thetreatment vessel 8 through the internal cracker The plant consists mainly of a cylindrical steel shell 3 acting as a treatment vessel for the acid sludge and a scrubber condenser 4 connected therewith. The.sludge,-together with a suitable quantity of cold water. is run off from the benzol washer into the treatment vessel 6 forming-the per part of the steel shell 3 which also comprises a heating chamber 8 in the form of a steam chest at its base. Low pressure steam is admitted to the heating chamber 6 through a pipe 1, provided with a stop valve la and tap lb, in order to heat upthe treatment vessel 5 prior to the admissionr'of acid sludge to the latter,.the steam passing from the chamber 6 through an outlet ll provided with a valve Ila. The sludge is admitted to the treatmentvessehby opening a duction of a'fiuid resin. As soon pipe 9, 'is used consistent with the complete elimination of benzol from the sludge and the prov a as benzol ceases to run from the separator, the treatment is dis- --continued by closing valve 'lla. to cut ofl! the openasteam. The contents of the treatment vessel arevthen allowed tostand for approximate- 1y fifteen minutes with continued admission of confined steam to the heating chamber 8 to allow of separation into upper layer of'liquid resin anda lower layer of acid liquor. the temperature of his final heating stage of the sludge being the which will result from the use of live steam at a pressure not to exceed ten pounds per square inch. The treatment vessel is provided with a valve in a pipe 8 connecting the treatment vessel with the benzol washer, .and when the sludge has been run in low pressure steam from the pipe I is admitted to the treatment vessel through an internal cracker pipe 9 disposed vertically in the treatment vessel. The steam passes from the pipe I by way of a branch I. provided with a stop valve Ito which isopened to admit sloping bottom in extended pe ripher'ally toform an inclined flange 5b bolted to a corresponding. fiange 81; formed. on the heating chamber 8. The sloping bottom so facilitates the separation of the layers in that it slopes downwardlyto run-off means 22 comprising a small cool; 23 and a main valve 24. The lower layer ,ofacid liquor is first run off through the small cock and pipe 25, and-when this operation iscomplete the main valve 24 is.

opened and the-thickliquid resin is run oil to a has set and may easily cooling tray 26.

Within three hours the resin be broken up and removed. a

By means of the method and apparatus described it will be seen the resin is separated in a liquid state without the addition of tar or oil.

Moreover, the products obtained from the treat-- ment of the sludge, that is light oils, acid and resinous residues are removed from the apparatus by gravity, no manual labour being involved in the process. The cold water addition to the sludge is sufllcient to maintain a requisite acid concentration and the quantity will be varied according to the condition of the sludge. The steam pressure required for the operation of the plant, that is to say for both the freeand the confined steam treatment, does not exceed ten pounds per square inch.

What we claim and desire to secure by Letters Patent is: t

1. An apparatus for the practice of the herein described method, embodying therein a treatment vessel, means for delivering a fixed quan tity of a mixture of sludge and water thereinto, heating means adjacent the bottom of said vessel, a cracker pipe extending into, and having outlets adjacent the bottom of, said vessel, whereby low pressure steam may be delivered into the sludge mixture adjacent the bottom of -sald' vessel, means controlling the steam supply for said cracker pipe, means comprising a small valve controlled pipe for withdrawing acid liquor from the bottom of said vessel, and means comprising a gate controlled main valve for withdrawing fluid resin irom the bottom of said vessel.

2. An apparatus for the practice of the heret in described method, embodying therein a treatmerit vessel having a sloping bottom, means for delivering a mixture of sludge and water thereinto, steam heating means below the bottom. of said vessel, a cracker pipe extending into, and having outlets adjacent the bottom of, said vessel, whereby low pressure steam may be delivered into the sludge mixture adjacent the bottom of said vessel, means controlling the steam supply for said cracker pipe, means comprising a small valve controlled pipe at the foot of the slope at the bottom of said vessel for withdrawing acid liquor from the bottom of said vessel, and means comprising a gate controlled main valve at the foot oi the slope at the bottom of said vessel for withdrawing fluid resin from the bottom of 25 said vessel.

WALTER FREDERICK CARR. THOMAS GEOFFREY WOOLHYOUSE. WILLIAM GREEN. 

